1. Field of the Invention
This invention relates to a magnet type fan clutch apparatus adapted to control the rotation of a cooling fan applied mainly to a vehicular internal combustion engine, operable with low noise and at a low fuel consumption and receiving a small shock during an initial period of the rotation thereof.
2. Description of the Related Art
The fan clutches for controlling the rotation of a cooling fan applied to a vehicular internal combustion engine include a liquid fan clutch, a hydraulically driven type fan clutch and the like. A liquid clutch is generally of the type in which the driving torque of a driving disc is transmitted to a case by an oil supplied to a torque transmission chamber. Concerning the construction of such a type of liquid clutch, a coupling apparatus (liquid clutch) is known (refer to Japanese Patent Publication No. 21048/1988) which is formed by, for example, dividing the interior of a sealed case into a torque transmission chamber and an oil reservation chamber by a partition, and providing a driving disc in the torque transmission chamber so that the driving disc can be rotated freely by the driving of a driving part, in which liquid clutch an oil in the oil reservation chamber is supplied from an outflow regulating hole formed in the partition into the torque transmission chamber with the oil the torque transmission chamber returned to the oil reservation chamber through a circulating passage. According to this type of liquid clutch, the driving torque of the driving disc is transmitted to the case by the oil supplied from the oil reservation chamber to the torque transmission chamber, and a fan fixed to the case is rotated, the cooling of a radiator of, for example, an automobile engine being thereby carried out. This type of liquid clutch is adapted to detect an atmospheric temperature by a bimetal, and increase the degree of opening of the outflow regulating hole when this temperature increases, to increase the quantity of the oil in the torque transmission chamber, a rotational frequency of the case, and a cooling effect by rotating the fan at a high speed.
However, the above-mentioned liquid fan clutch and hydraulically driven type fan clutch have problems which will be described below.
Namely, when an engine is restarted with a large quantity of oil existing in a torque transmission chamber of a liquid fan clutch, or when an engine is suddenly accelerated during the travel of a vehicle, a sudden increase in the rotational frequency of a driven case (cooling fan) occurs, though it continues for a short period of time, due to the oil existing in a large quantity in the torque transmission chamber, following up the acceleration of a disc on the driving side. This phenomenon is generally called a phenomenon of xe2x80x9caccompanied rotationxe2x80x9d, which causes the noise of a fan and unpleasant sensation due to the noise to occur, and fuel consumption to lower.
The conspicuousness of the phenomenon of xe2x80x9caccompanied rotationxe2x80x9d in a related art liquid fan clutch occurring during the restarting of the engine increases in proportion to the quantity of the oil in the torque transmission chamber. As a method of solving this problem, for example, Japanese Patent Publication No. 21048/1988 proposes a liquid fan clutch formed so that an oil flowing out from an outflow regulating hole of a partition is once guided to a diametrically opposite side, from which the oil is supplied to the interior of a torque transmission chamber.
In such a structure, the oil does not flow from an oil reservation chamber into the torque transmission chamber when the engine is stopped with the oil substantially not existing in the torque transmission chamber but existing in large quantities in the oil reservation chamber, so that the phenomenon of xe2x80x9caccompanied rotationxe2x80x9d does not occur. However, this structure proves not effective in restarting an engine after the engine was stopped with a large quantity of oil existing in the torque transmission chamber, and in preventing the occurrence of the xe2x80x9caccompanied rotationxe2x80x9d when the engine is suddenly accelerated during the travel of the vehicle.
In the case of a hydraulically driven type fan clutch apparatus, a rotational frequency can be controlled to be at an arbitrary level but hydraulic devices, such as an oil reservoir tank, hydraulic pipes, an oil cooler, a relief valve, etc. are needed. Therefore, this fan clutch apparatus requires a large space, and costs much.
The present invention has been made in view of these circumstances, and provides a magnet type fan clutch apparatus in which the simplification of the construction and the reduction of the cost are attained by uniting a magnet coupling and an electromagnetic clutch with each other.
According to one aspect of the present invention, the magnet type fan clutch apparatus has a combination of a magnet coupling and an electromagnetic clutch with a fan fixed to the magnet coupling.
According to another aspect of the present invention, the magnet type fan clutch apparatus has an electromagnetic clutch formed of a clutch rotor supported on a driving shaft and having an exciting coil supported on an outer part and incorporated in the clutch rotor, and an armature fixed to a disc supported rotatably on the driving shaft via a bearing; and a magnet coupling which has a permanent magnet rotary body supported rotatably on the driving shaft via a bearing and provided at an outer circumference thereof with a fan fixed thereto, and a hysteresis member or a conductor fixed to the disc so that the hysteresis member or a conductor is opposed to the permanent magnet with a narrow clearance left therebetween, and which is formed so that the permanent magnet rotary body and disc are rotated together owing to an attraction working between the permanent magnet and the hysteresis member or conductor, the magnet coupling being ON/OFF controlled by the electromagnetic clutch.
According to still another aspect of the present invention, the magnet type fan clutch apparatus has an electromagnetic clutch formed of a clutch rotor supported on a driving shaft, an exciting coil provided in the interior of the clutch rotor and supported on an outer part, and an armature held longitudinally movably on the portion of a driven side housing supported rotatably on the clutch rotor via a bearing which is on the side of the exciting coil; and a magnet coupling which has a permanent magnet rotary body, to which a fan is fixed, supported rotatably via a bearing on a driven shaft made integral with the driven side housing, and a disc provided with a hysteresis member or a conductor opposed to the permanent magnet rotary body with a narrow clearance left therebetween, and mounted on the driven shaft, and which is formed so that the permanent magnet rotary body and disc are rotated together owing to an attraction working between the permanent magnet and the hysteresis member or conductor, the magnet coupling being ON/OFF controlled by the electromagnetic clutch.
According a further aspect of the present invention, the magnet type fan clutch apparatus has an electromagnetic clutch formed of a clutch rotor supported on a driving shaft, an exciting coil supported on a flange which is supported rotatably on the driving shaft via a bearing and fixed to an outer part, and an armature held longitudinally movably via a bearing on the portion of a driven side cylinder supported rotatably on the driving shaft which is on the side of the exciting coil; and a magnet coupling which is formed of a permanent magnet, to which a fan is fixed, supported rotatably on an outer circumference of the driven side cylinder via a bearing, a hysteresis member or a conductor opposed to the permanent magnet rotary body with a narrow clearance left therebetween, and fixed on an outer circumference of the driven side cylinder, and which is formed so that the permanent magnet rotary body and driven side cylinder are rotated together owing to an attraction working between the permanent magnet and the hysteresis member or conductor, the magnet coupling being ON/OFF controlled by the electromagnetic clutch.
According to another aspect of the present invention, the magnet type fan clutch apparatus has a magnet coupling formed of a permanent magnet rotary body mounted fixedly on a driven shaft the rotation of which is controlled by an electromagnetic clutch, and a fan-carrying disc which has a hysteresis member or a conductor opposed to the permanent magnet rotary body with a narrow clearance left therebetween, and which is supported rotatably on the driven shaft via a bearing; and formed so that the permanent magnet rotary body and fan-carrying disc are rotated together owing to an attraction working between the permanent magnet on the permanent magnet rotary body and the hysteresis member or conductor, the magnet coupling being ON/OFF controlled by the electromagnetic clutch.
According to still another aspect of the present invention, the magnet type fan clutch apparatus has an electromagnetic clutch formed of a clutch rotor supported rotatably on a non-rotatably fixed shaft via a bearing, an exciting coil mounted fixedly on the fixed shaft and provided in the clutch rotor, and an armature longitudinally movably held on a rear surface, i.e. the surface of the permanent magnet rotary body supported rotatably via a bearing on the fixed shaft which is on the side of the exciting coil; and a magnet coupling which is formed of a permanent magnet rotary body supported rotatably on the fixed shaft via a bearing, and a disc, to which a fan is fixed, provided with a hysteresis member or a conductor opposed to the permanent magnet rotary body with a narrow clearance left therebetween, and which is formed so that the permanent magnet rotary body and disc are rotated together owing to an attraction working between the permanent magnet rotary body and the hysteresis member or conductor, the magnet coupling being ON/OFF controlled by the electromagnetic clutch.
The electromagnetic clutches in the above-described magnet type fan clutch apparatuses are formed so that the electromagnetic clutches are ON/OFF controlled in accordance with a cooling water temperature, a degree of opening of a throttle, an engine speed and an operation of an air-conditioner switch, and so that the rotation of the magnet coupling, i.e. the rotation of the fan can be controlled by the ON/OFF controlling of the electromagnetic clutch. In the magnet type fan clutch apparatus according to the present invention, thermal ferrite is substituted for the permanent magnet, and an eddy current material (conductor) or iron or ferrite stainless steel for the hysteresis member. As a rotary driving power source, a system for driving the clutch rotor by an engine directly or via a pulley or a gear; or a special motor, etc. provided separately from an engine can be used.
When the exciting coil of the electromagnetic clutch in the above-described magnet type fan clutch apparatuses is turned on, the armature is attracted to the clutch rotor, so that the clutch rotor and armature, and disc or driven side housing or cylinder are rotated together. Consequently, the fan is rotated by the magnet coupling. Since the magnet coupling transmits torque by a magnetic force of the permanent magnet during this time, the magnet coupling slips and starts a cushioning action. Therefore, when the electromagnetic clutch is turned on, a load is low, and the noise of the fan can be reduced remarkably. When the electromagnetic clutch is turned off, the armature leaves the clutch rotor, so that a rotational speed of the magnet coupling decreases greatly or the magnet coupling stops. Consequently, a rotational speed of the fan decreases greatly, or the fan stops.
When the electromagnetic clutch is turned on in the magnet type fan clutch apparatus of a system in which the rotation of a driving shaft is controlled directly by an electromagnetic clutch, the driving shaft is rotated, so that a fan is rotated by a magnet coupling formed of a permanent magnet rotary body mounted fixedly on this driving shaft and a fan-carrying disc supported rotatably on the same shaft. During this time, the magnet coupling also starts a cushioning action in the same manner. Therefore, when the electromagnetic clutch is turned on, a load is low, and the noise of the fan can be reduced. When the electromagnetic clutch is turned off, a rotational speed of the driving shaft decreases greatly, or the driving shaft stops. Consequently, a rotational speed of the fan decreases greatly, or the fan stops.
Thus, according to the present invention, the rotation of the fan can be controlled by turning on and off the electromagnetic clutch. Since the electromagnetic clutch is ON/OFF controlled in accordance with a cooling water temperature, a degree of opening of a throttle, an engine speed and an operation of an air-conditioner switch, the rotation of the fan can be controlled accurately and stably.
In the above-described magnet type fan clutch apparatus according to the present invention, so-called magnetic energy is utilized. Therefore, especially in, the disc-carrying magnet type fan clutch apparatuses except the magnet type fan clutch apparatus using such a cylinder type magnet coupling as in the fourth-mentioned invention, the entry of the ambient dust (dust, metal powder, etc.), water, etc. into a very narrow clearance between the permanent magnet and a conductor causes a function disorder to occur in some cases. Therefore, in the magnet type fan clutch apparatus, taking measures to prevent the entry of dust (powdered dust, metal powder, etc.), water, etc. into a very narrow clearance between the permanent magnet and conductor is needed.
As such measures, the present invention is provided with structures described in 7th to 12th inventions.
Namely, the magnet type fan clutch apparatus according to a 7th invention is provided with a seal structure between the circumferential portion of such a disc as mentioned above which is on the outer side of a conductor and the circumferential portion of a permanent magnet rotary body which is on the outer side of a permanent magnet.
The magnet type fan clutch apparatus according to an 8th invention is provided with a labyrinth seal type structure as the seal structure.
The magnet type fan clutch apparatus according to a 9th invention is provided with a spiral type seal structure as the labyrinth seal type structure.
The magnet type fan clutch apparatus according to a 10th invention is provided with a ventilation mechanism between such a disc as mentioned above and a permanent magnet rotary body.
The magnet type fan clutch apparatus according to an 11th invention is provided with a ventilation mechanism made by forming guide grooves, which are capable of obtaining an effect identical with that of guide vanes of a pump, in the opposed surfaces of a conductor on such a disc as mentioned above and a permanent magnet rotary body.
The magnet type fan clutch apparatus according to a 12th invention is provided on an outer circumferential end portion of the surface of such a disc as mentioned above which is opposed to a permanent magnet rotary body with ventilation blades and/or on an inner side of a conductor with ventilation vanes, over the whole circumferences thereof so that the blades and/or vanes project incliningly or radially.
The magnet type fan clutch apparatus according to a 13th invention is provided on the inner side of a: permanent magnet of a permanent magnet rotary body which is opposed to a disc with ventilation vanes and/or on an outer circumferential side of the permanent magnet with ventilation blades so that the vanes and/or blades project radially.
A combination of the permanent magnet of the magnet coupling and the hysteresis member or conductor in the magnet type fan clutch apparatuses of the first to 12th inventions can be formed of an eddy current member provided on a front surface of an iron plate or hysteresis member and a permanent magnet (14th invention).